The invention relates to a forward structure of a motor vehicle, particularly of a passenger car.
From the series production of motor vehicles, it is known to dispose an energy absorbing element, particularly a foam-type impact absorbing element, in front of a bumper cross member assigned to the forward structure of the vehicle in order to absorb energy in the event of an impact.
From German Patent document DE 102 34 038 A1, a forward structure of a passenger car is known, which includes a bumper cross member in front of which—viewed in the driving direction—a part made of a foamed material is disposed. In order to pass the pendulum test and the lower leg test, German Patent document DE 102 34 038 A1 suggests that the foamed part, at least partially, has knobs or indentations. By means of this knob structure, foams or foamed materials with a higher specific gravity can be used. This reduces the penetration depths of the pendulum during the pendulum impact.
In the case of increasingly further reduced deformation spaces in the forward structure regions of the vehicle, under certain circumstances, the knobs or indentations may not be sufficient for implementing an optimal energy reduction.
It is therefore an object of the invention to improve the forward structure of a motor vehicle, particularly of a passenger car, such that, while the installation space is reduced, an optimal energy reduction and thereby the best-possible protective function for a leg impact is ensured.
According to the invention, a forward structure of a motor vehicle, particularly a passenger car, includes a bumper cross member, and an energy type impact absorbing element, disposed in front of the bumper cross member—viewed in the driving direction. A plurality of recesses are shaped into the forward-side outer contour of the energy absorption element. At least several of the recesses completely penetrate the energy absorption element along its entire depth, whereby a plurality of breakthroughs are arranged in the energy absorption element.
Advantageous embodiments of the invention are described herein.
The bumper cross member is connected to the supporting structure of the passenger car forward structure and is used for absorbing and transmitting impact forces into the supporting structure. Crash boxes, which are part of the supporting structure, are preferably arranged between the bumper cross member and the two forward side members.
As a rule, the energy absorption element ensures the energy reduction by compressing the foam material that is used. As much energy as possible should be reduced when an accident occurs with another vehicle, so that hard foam is used for this purpose. However, in the case of accidents with a pedestrian, large penetration depths should be made possible, so that the load values, such as the knee bending angles, the shearing values, and the acceleration values, can be minimized. A relatively soft foam is required for this purpose.
A plurality of recesses are shaped into the forward-side outer contour of the energy absorption element disposed in front of the bumper cross member, which recesses completely penetrate the energy absorption element along its entire depth. A plurality of hole-like recesses are therefore arranged in the energy absorption element. As a result, harder foams or materials can be used in order to permit the energy reduction required for the pendulum impact. Simultaneously, the material of the bridge regions surrounding the recess can be deflected into the recesses. As a result of the breakthroughs according to the invention, the residual block length of the energy absorption element can be further reduced.
In an advantageous further development of the invention, the recesses extend almost along the entire width of the energy absorption element. As a result, a relatively uniform energy reduction becomes possible over the entire forward structure. This effect is promoted when the recesses are situated at substantially the same level.
In order to compensate for the lack of initial stiffness of the energy absorption element, crash-box-like elements may extend, at least partially, into one of the breakthroughs respectively. Particularly with respect to an improved initial stiffness during the leg impact, this has a positive effect on the energy absorption. Simultaneously, the bridge regions between the recesses supply the softness of the energy absorption element desired for the pedestrian impact. When the foam depth is low, the crash-box-like elements cause an optimal utilization of the deformation path in order to compensate for the lack of initial stiffness of the foam part.
Manufacturing advantages are achieved when several of the crash-box-like elements are combined in an insert. The insert can therefore easily be placed, particularly inserted, from the rear into the breakthroughs of the energy absorption element and can be fastened together with the energy absorption element on the bumper cross members.
It was found that a truncated cross-section of the crash-box-like elements results in optimal energy absorption values, in which case the base of the truncated cone is oriented to the back side of the energy absorption element; that is, the narrower truncated cone head is oriented toward the outer contour of the energy absorption element.
Additional manufacturing advantages are achieved when the crash-box-like element has a truncated construction. It may then be manufactured, for example, as a deep-drawn part.
The residual block length can be further reduced when the side walls of the crash-box-like element are provided with cutouts, which result in wall webs. Depending on the demanded energy absorption values, a simple adaptation can take place by selecting the material type, the material thickness or by varying the number and the size of the cutouts. Desired bending points may be provided in the webs, at which bending points the component would fail first.
In a preferred embodiment of the invention, no crash-box-like elements which penetrate the breakthroughs may be provided in a defined region of the energy absorption element. In addition, breakthroughs can be completely eliminated in this defined region and instead recesses may be provided to a predefined depth.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings.